Firearms having inertial firing pins which, when struck by the hammer of the firearm, are driven forward to strike and discharge a cartridge are well known. Several devices have been proposed to selectively lock the firing pin in order to prevent the firearm from being accidentally discharged. Such accidental discharge may occur in the event that the firearm is dropped from a distance of several feet and subsequently lands in such a manner that inertia carries the firing pin forward, thus causing it to strike the cartridge.
Manual firing pin locks are well known. They are typically located within the slide of an automatic or semiautomatic pistol and function to prevent the firing pin from contacting a chambered cartridge when activated. There is a tendency not to activate such manually operated firing pin lock mechanisms when it is anticipated that rapid and unexpected use of the gun may be required, e.g. during law enforcement or combat use. In such situations, the user does not want to be forced to remember to disengage the firing pin lock under stressful conditions, nor does he want to take the time to do so.
Passive firing pin locks such as that described in U.S. Pat. No. 4,555,861 issued to Khoury are known. Such devices have the advantage of not requiring the user to manually engage and disengage the lock. Rather, the lock is automatically engaged when the trigger is in the non-depressed or unactuated position and is automatically disengaged when the trigger is in the depressed or actuated position.
Prior art passive firing pin locks such as the Khoury device suffer, however, from the inherent deficiency that the firing pin is necessarily free to travel forward any time the trigger is depressed, including during the chambering of a cartridge. In such firearms, a malfunction of the disconnector or sear can cause a normally semiautomatic gun to function in a fully automatic mode. A semiautomatic firearm discharges one cartridge each time the trigger is pulled. A fully automatic firearm continues to fire as long as the trigger is depressed and cartridges remain to be fired. Unexpected fully automatic operation could result in the firearm being discharged in an inappropriate direction, possibly resulting in injury or death. Since fully automatic operation requires a stronger grip on the firearm and a firm stance to maintain control of the firearm.
Additionally, since in the Khoury device the firing pin lock does not re-engage the firing pin until the trigger is released, it is possible that an accidental discharge could occur prior to releasing the trigger. For example, in a combat environment the firearm could be struck by a bullet or shrapnel immediately after the firearm has been fired but prior to releasing the trigger. During this time the passive firing pin lock of the Khoury device would be inactive and therefore would not function to prevent the firing pin from being driven forward and discharging the weapon. Therefore, it is possible that an accidental discharge could occur. Also, it is conceivable that the user could fall and permit the firearm to strike a hard surface prior to releasing the trigger, thus driving the firing pin forward and accidentally discharging the firearm.
It would therefore be desireable to lock the firing pin in a retracted position at all times except when it is explicitly desired that the firearm be discharged. This would prevent both unexpected fully automatic operation and accidental discharge.
Also, such contemporary passive firing pin locks are comparatively complex in their structure. The Khoury device is typical in this regard and includes a double lever and pin arrangement which is comparatively prone to malfunction due to excessive wear, contamination, or breakage. It would therefore be desirable to provide a mechanically simpler mechanism for preventing undesired forward motion of the firing pin.
Double action semi-automatic pistols are also well known in the art. Pulling the trigger of a double action pistol both cocks the hammer and causes it to fall upon the firing pin. This eliminates the need to separately cook the hammer prior to pulling the trigger. Thus, double action pistols are more effective when quick and unexpected use may be required.
Since the hammer of a double action semi-automatic pistol does not have to be separately cocked and the pistol is therefore capable of being fired by merely pulling the trigger, it is often desireable to keep a cartridge in the chamber. This permits rapid use of the pistol by merely aiming and pulling the trigger. To chamber a cartridge, the slide is pulled back and released, thereby stripping the top cartridge from the magazine and loading it into the chamber. This action also cocks the hammer of the pistol and leaves the hammer in a cocked position.
After chambering a cartridge, the hammer remains in a cocked position such that pulling the trigger will discharge the weapon. Various safety mechanisms are known for preventing inadvertent discharge of the firearm when the trigger is pulled while the hammer is in a cocked position. Such safety mechanisms generally either prevent the sear from releasing the hammer, lock the hammer in the cocked position, or prevent the trigger from being pulled. However, as with the manual firing pin lock, the use of such a safety mechanism is often undesirable when rapid and expected use is likely.
Thus, it is often desireable to have a cartridge chambered; but due to the double action operation of the pistol, it is not necessary to maintain the hammer in a cocked position. Indeed, it is frequently more desireable to maintain the hammer in a decocked position. This is because it takes a substantially greater amount of force to depress the trigger and discharge the firearm when the hammer is in the decocked position. As such, additional force must be provided by the user to cock the hammer, instead of merely releasing it to fall upon the firing pin (i.e. it requires a much more deliberate action to depress the trigger of a decocked double action firearm than to depress the trigger of a cocked double action firearm). This additional force is necessary to overcome the hammer spring tension as the hammer is raised to the cocked position. Such additional force makes an accidental discharge less likely. For example, if a foreign object inadvertently engages the trigger, it is much less likely that an accidental discharge will occur if the hammer is decocked.
Therefore, a common problem associated with double action semi-automatic pistols is the safe lowering of the hammer after manually chambering a cartridge. It may be desired to lower the hammer, thus decocking the firearm, when the gun is to be carried in a holster, stored for an extended period of time, or when it is otherwise desireable not to have the hammer in a cocked position. Many police departments require that their officers carry their firearm with a cartridge in the chamber and the hammer in a decocked position.
A common method for decocking a firearm is to grasp the hammer with the fingers of one hand while holding the firearm in the other hand and pulling the trigger. Grasping the hammer prevents it from falling forcefully upon the firing pin and thus discharging the gun. However, occurrences of inadvertent discharges while attempting this procedure are not uncommon. Since such inadvertent discharges can cause injury and death, it is very desireable to provide a means for lowering the hammer of such a firearm in a safe and convenient manner.
Various decocking or hammer drop mechanisms are known. One such mechanism slowly lowers the hammer to its decocked position such that the hammer does not strike the firing pin with enough force to drive the firing pin into the chambered cartridge. Another mechanism rotates a portion of the firing pin out of the path of the falling hammer such that the hammer cannot strike the end of the firing pin. In this instance the trigger may be pulled to cause the hammer to drop, since it is prevented from striking the displaced firing pin. Alternatively, the mechanism which displaces the portion of the firing pin may also cause the hammer to drop.
A means for lowering the hammer in a single action semi-automatic pistol would likewise be desireable since it is often desired to maintain a single action semi-automatic pistol with a chambered cartridge. This is true even though the hammer of a single action pistol must be separately cocked prior to firing the first cartridge.
Additionally, in the prior art, much weight has been given to the ability of the barrel bushing to firmly secure the front end of the barrel in position. The accuracy of the firearm depends upon the repeatability with which the barrel can be repositioned relative to the sights.
Various bushings for repositioning the forward end of the barrel after each shot are well known. The simplest of such bushings merely receive the front end of the barrel, holding it in place until the firearm is discharged. During discharge, the bushing travels rearward along the barrel. When the barrel unlocks from the slide, the bushing permits slight rotation of the barrel relative to the slide. Such rotation is necessary to accommodate the unlocking/locking motion of the barrel. Such simple bushings must therefore incorporate a slightly oval, elongated, or oversized central aperture.
Through the use of close tolerances, an attempt is made to securely restrain the forward end of the barrel within the bushing prior to discharging the firearm. The requirement for such close tolerances causes the firearm's accuracy to degrade as the bushing wears and the tolerances are lost. Also, close tolerances require the mechanism be maintained comparatively free from contamination. Dirt, sand, lint, and other contaminants can cause the bushing to bind upon the barrel and jam the firearm. The use of close tolerances increases the rate at which the barrel bushing wears due to friction. Fabrication of barrel bushings having close tolerances is comparatively difficult and expensive.
Thus, the prior art has concentrated efforts for achieving superior accuracy upon the ability of the barrel bushing to firmly secure the forward end of the barrel in position. Other mechanisms, such as Colt's collet type barrel bushing, disclosed in U.S. Pat. No. 3,564,967 issued to La Violette have been used to achieve this result. All such methods of firmly securing the forward end of the barrel in position are characterized by the requirement for closely held tolerances which tend to degrade over time and thus cause the firearm's accuracy to deteriorate.
Another common problem with prior art bushings is cracking due to the repeated application of stress when the gun is fired. This is particularly true of the Colt collet type bushing wherein comparatively delicate fingers secure the barrel in place. Such fingers are subject to the development of stress cracks. Consequently, they occasionally break off whereupon they may cause the gun to jam.
It would be desirable to repeatably position the barrel without requiring that the forward end of the barrel be firmly secured in place. It would also be desireable to eliminate the need for close tolerance in the fabrication of barrel bushings. Additionally, it would be desireable to provide a barrel bushing which is not susceptible to malfunction due to stress.
In addition, colored inlays formed upon the front and rear sights of firearms for aiding the user in the aiming process are well known. Typically a single round or rectangular inlay is provided upon the firearms front sight and two round inlays are provided on either side of the central groove of the rear site. Such inlays are typically colored either white or red to provide a stark contrast to the deep blue or black color of the gun sights. The use of colored inlays provides highly visible reference points by which the user can quickly align the sights upon a target.
Such inlays are used by aligning the inlay formed upon the front sight between the two inlays formed upon the rear sights. This process is hastened by the ease with which the colored inlays are perceived by the user. The red or white inlays can be quickly spotted and rapidly brought into rough alignment.
However, precise alignment of the prior art inlays is relatively difficult. The curved peripheries of the round inlays used upon the rear and/or front sights do not provide an easy means for judging alignment. In the prior art, the user must either align round rear inlays to a round front inlay or round rear inlays to a rectangular front inlay.
As will be recognized, it is difficult to align curved lines to each other or to a straight line. The curved lines do not provide a single reference for alignment, but rather present the user with the task of defining a reference. The user must align the round inlay by concentrating upon some portion thereof. For example, the user may attempt to visually determine the center point of the round inlay on the front sight and align it to similarly determined center points on round inlays of the rear sights.
Thus, although prior art firearms have proven generally suitable for their intended purposes, they possess inherent deficiencies which detract from their safe use and reduce accuracy below that theoretically obtainable. This detracts from their overall effectiveness in the marketplace.
In view of the shortcomings of the prior art, it is desirable to provide an improved firearm having a trigger actuated passive firing pin lock, a convenient and safe means for lowering the hammer of a firearm having a chambered cartridge, a barrel bushing which accurately repositions the forward end of the barrel relative to the sights, and sight inlays which allow the user to quickly and precisely aim the firearm.